Log Message:
cbindgen: update to 0.28.0.

# 0.28.0

      * Parse unsafe attributes in https://github.com/mozilla/cbindgen/pull/1020
      * Fix local override of enum prefix-with-name by jsgf in \ 
https://github.com/mozilla/cbindgen/pull/1006
      * Add rename-all=prefix in https://github.com/mozilla/cbindgen/pull/1021
      * ir: add support for UnsafeCell and SyncUnsafeCell by alekitto in \ 
https://github.com/mozilla/cbindgen/pull/1003
      * Implement mangling for arrays in \ 
https://github.com/mozilla/cbindgen/pull/1022
      * Fix: Ignore `CARGO_BUILD_TARGET` in tests by bryango in \ 
https://github.com/mozilla/cbindgen/pull/1010
      * Newline for each field for constexpr field constants by youknowone in \ 
https://github.com/mozilla/cbindgen/pull/988
      * Fix clippy warnings by youknowone in \ 
https://github.com/mozilla/cbindgen/pull/1026
      * Add aarch64/arm64 to CI by NickeZ in \ 
https://github.com/mozilla/cbindgen/pull/1036
      * Add `unstable_ir` feature flag that makes the ir pub by heesooy in \ 
https://github.com/mozilla/cbindgen/pull/1011
      * Support generated a symbols file by TheElectronWill in \ 
https://github.com/mozilla/cbindgen/pull/916